Tiltrotor aircraft rotating proprotor assembly

ABSTRACT

An aircraft including a nacelle configured as a housing for an engine and disposed at a fixed location relative a wing member; a proprotor housing coupled to the nacelle, the proprotor housing configured to selectively rotate between a horizontal orientation and a non-horizontal orientation; a door hingedly coupled to the proprotor housing by a first hinge joint and hingedly coupled to the nacelle by a second hinge joint. An aspect includes an aircraft with a proprotor coupled to a wing member, the proprotor comprising a forward portion and an aft portion; wherein the forward portion is configured to selectively pivot between a horizontal orientation and a non-horizontal orientation about a conversion axis C; and wherein when the forward portion is in a non-horizontal orientation, the aft portion is in a horizonal orientation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/127,115, filed Sep. 10, 2018, which is a continuation-in-part of U.S.patent application Ser. No. 15/661,129, filed Jul. 27, 2017, which is acontinuation-in-part of U.S. patent application Ser. No. 15/448,415,filed Mar. 2, 2017, and U.S. patent application Ser. No. 15/448,136,filed Mar. 2, 2017. Each patent application identified above isincorporated herein by reference in its entirety.

BACKGROUND Technical Field

The present disclosure relates to an aircraft, and more particularly, toa tiltrotor aircraft having a rotating proprotor assembly.

Description of Related Art

Certain tiltrotor aircraft, such as the Bell Helicopter Valor V-280tiltrotor aircraft, employ a propulsion system on a wing member with afixed nacelle that encloses an engine and a movable (rotatable)proprotor gearbox (PRGB) system that drives the rotor blades. The PRGBsystem is rotatable relative to the nacelle to convert between avertical flight mode and a forward flight mode and vice versa. Inoperation, as the rotation of the PRGB can cause at least one of thefollowing issues: unwanted vibrations transmitted from the PRGB to otheraircraft components and create a space behind the rotation axis of thePRGB during the transition to the vertical flight mode and during theflight mode that interrupts the aerodynamic profile of the nacellepropulsion system. Therefore, there what is needed is an apparatus thataddresses one or more of the foregoing issues, and/or one or more otherissues.

SUMMARY

In a first aspect, there is an aircraft, including a nacelle configuredas a housing for an engine and disposed at a fixed location relative awing member; a proprotor housing coupled to the nacelle, the proprotorhousing configured to selectively rotate between a horizontalorientation and a non-horizontal orientation; a door hingedly coupled tothe proprotor housing by a first hinge joint and hingedly coupled to thenacelle by a second hinge joint, wherein the first and second hingejoints are configured to move the door from a closed position when theproprotor housing is in a horizontal orientation to an open positionwhen the proprotor housing is in a non-horizontal orientation.

In an embodiment, there is an arm disposed between the first and secondhinge joints, the arm configured to impart movement from the first hingejoint to the second hinge joint.

In one embodiment, the first hinge joint is at least partially disposedin a slot in the proprotor housing.

In a second aspect, there is an aircraft including a proprotor coupledto a wing member, the proprotor comprising a forward portion and an aftportion; wherein the forward portion is configured to selectively pivotbetween a horizontal orientation and a non-horizontal orientation abouta conversion axis C; and wherein when the forward portion is in anon-horizontal orientation, the aft portion is in a horizonalorientation.

In an embodiment, the conversion axis C is disposed in the forwardportion of the proprotor.

In another embodiment, the wing member comprises a first rib and asecond rib.

In still another embodiment, the forward portion is actuated by acantilevered spindle disposed outboard of the second rib.

In one embodiment, there are bearings to support the cantileveredspindle, the bearings are associated with the first and second ribs.

In an embodiment, there is an actuator is disposed outboard of the firstrib and is configured to engage the cantilevered spindle to pivot theforward portion in a non-horizontal orientation.

Other aspects, features, and advantages will become apparent from thefollowing detailed description when taken in conjunction with theaccompanying drawings, which are a part of this disclosure and whichillustrate, by way of example, principles of the inventions disclosed.

DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the embodiments of thepresent disclosure are set forth in the appended claims. However, theembodiments themselves, as well as a preferred mode of use, and furtherobjectives and advantages thereof, will best be understood by referenceto the following detailed description when read in conjunction with theaccompanying drawings, wherein:

FIG. 1 is a perspective view of a tiltrotor aircraft in the verticalflight mode (helicopter mode), according to one example embodiment;

FIG. 2 is a perspective view of a tiltrotor aircraft in the forwardflight mode (airplane mode), according to one example embodiment;

FIG. 3A-3B is a partial perspective view of a nacelle and a PRGB door inforward flight mode, according to one example embodiment;

FIG. 4 is a series of side views of the nacelle and a PRGB door inforward flight mode, transition modes, and vertical flight mode,according to one example embodiment;

FIGS. 5A-5C are perspective views of a PRGB door and hinge fittings forconnecting to the PRGB system and with a bogie mechanism, according toan example embodiment;

FIG. 6 is a partial elevation view of a PRGB door in the closed positionfor forward flight mode, according to an exemplary embodiment;

FIG. 7 is a partial elevation view of a PRGB door in the open positionfor vertical flight mode, according to an exemplary embodiment;

FIG. 8 is a perspective view of an assembled door roller mechanism,according to an exemplary embodiment;

FIG. 9 is an exploded view of a door roller mechanism, according to anexemplary embodiment;

FIG. 10 is a perspective view of a track housing, according to anexemplary embodiment;

FIG. 11 is a perspective view of a roller track in a track housing,according to an exemplary embodiment; and

FIG. 12 is an enlarged perspective view of an entry end of the rollertrack assembly where the roller mechanism is inserted for riding onroller track surfaces, according to an exemplary embodiment.

FIG. 13A is perspective view of a PRGB door including a pair of doorroller mechanisms and tracks, according to an exemplary embodiment;

FIG. 13B is a perspective view of a PRGB door including a pair oftelescoping struts, according to one embodiment;

FIG. 14A is a perspective view of a PRGB door with a roller track;according to an exemplary embodiment;

FIGS. 14B-14E are perspective views of a PRGB door with a roller trackand a nacelle with a roller mechanism converting from forward flightmode to vertical flight mode, according to exemplary embodiments;

FIG. 14F is a perspective view of a roller mechanism engaged with aroller track, according to an exemplary embodiment;

FIGS. 15A-15B are perspective views of a PRGB door pivotally connectedto the proprotor pylon, according to exemplary embodiments;

FIG. 16 is a perspective view of a flexible PRGB door, according to anexemplary embodiment;

FIGS. 17A-17B are perspective views of a pair of PRGB doors, accordingto exemplary embodiments;

FIG. 17C is a schematic cross-sectional view of a linkage for a pair ofPRGB doors, according to an exemplary embodiment.

FIGS. 18A-18B are side views of a proprotor pylon having a center ofrotation in-line with the wing pivoting on a cantilevered spindle but afixed aft pylon fairing converting from forward flight to verticalflight;

FIG. 19 is a schematic illustration of a pivot mechanism including thecantilevered spindle for the proprotor pylon in FIGS. 18A-18B, accordingto one example embodiment;

FIG. 20 is a partial perspective view of a nacelle with a door systemand a PRGB door in forward flight mode, according to one exampleembodiment;

FIG. 21 is a partial perspective view of the door system in FIG. 20;

FIG. 22 is a partial section view looking through the movable proprotorhousing to the door system in FIG. 20 and the PRGB door in verticalflight mode, according to one example embodiment;

FIG. 23 is a partial schematic side view of the nacelle according to oneexample embodiment;

FIG. 24 is a schematic front view of the door roller mechanism in atrack assembly according to one example embodiment;

FIG. 25 is a front view of the aft end of the track assembly accordingto one example embodiment; and

FIG. 26 is a partial schematic side view of the nacelle according to oneillustrative embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of aerodynamic fairing mechanisms andassemblies for a rotating proprotor are described below. In the interestof clarity, all features of an actual implementation may not bedescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedeveloper's specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure.

In the specification, reference may be made to the spatial relationshipsbetween various components and to the spatial orientation of variousaspects of components as the devices are depicted in the attacheddrawings. However, as will be recognized by those skilled in the artafter a complete reading of the present application, the devices,members, apparatuses, etc. described herein may be positioned in anydesired orientation. Thus, the use of terms such as “above,” “below,”“upper,” “lower,” or other like terms to describe a spatial relationshipbetween various components or to describe the spatial orientation ofaspects of such components should be understood to describe a relativerelationship between the components or a spatial orientation of aspectsof such components, respectively, as the device described herein may beoriented in any desired direction.

The same or similar features of one or more embodiments are sometimesreferred to with the same reference numerals within a figure or amongfigures. However, one or more features having the same reference numeralshould not be construed to indicate that any feature is limited to thecharacteristics of another feature having the same reference numeral, orthat any feature cannot already have, or cannot be modified to have,features that are different from another feature having the samereference numeral.

Referring to FIGS. 1 and 2 in the drawings, a tiltrotor aircraft 101 isillustrated. Tiltrotor aircraft 101 can include a fuselage 103, alanding gear 105, a tail member 107, and a wing member 109, a propulsionsystem 111, and a propulsion system 113. Each propulsion system 111, 113includes a nacelle 200, 201 disposed at a fixed location relative towing member 109 and a rotatable gearbox proprotor system 115, 117respectively. Each rotatable proprotor gearbox system 115, 117 has aplurality of rotor blades 119, 121, respectively. The position of therotatable proprotor gearbox systems 115, 117 as well as the pitch of therotor blades 119, 121, can be selectively controlled in order toselectively control direction, thrust, and lift of the tiltrotoraircraft 101.

FIG. 1 illustrates tiltrotor aircraft 101 in vertical flight mode(helicopter mode), in which the rotatable proprotor gearbox systems 115,117 are positioned substantially vertical to provide a lifting thrust.FIG. 2 illustrates tiltrotor aircraft 101 in forward flight mode(airplane mode), in which the rotatable proprotor gearbox systems 115,117 are positioned substantially horizontal to provide a forward thrustin which a lifting force is supplied by the wing member 109. It shouldbe appreciated that tiltrotor aircraft can be operated such thatrotatable proprotor gearbox systems 115, 117 are selectively positionedbetween the airplane mode and the helicopter mode, which can be referredto as a conversion mode.

Further, propulsion systems 111, 113 are illustrated in the context oftiltrotor aircraft 101; however, propulsion systems 111, 113 can beimplemented on other tiltrotor aircraft. For example, an alternativeembodiment may include a quad tiltrotor that has an additional wingmember aft of the wing member 109, the additional wing member can haveadditional propulsion systems similar to propulsion systems 111, 113. Inanother embodiment, propulsion systems 111, 113 can be used with anunmanned version of tiltrotor aircraft 101. Further, propulsion system111, 113 can be integrated into a variety of tiltrotor configurations.

The propulsion system 113 is substantially symmetric to the propulsionsystem 111; therefor, for the sake of efficiency certain features willbe disclosed only with regard to propulsion system 111. However, one ofordinary skill in the art would fully appreciate an understanding ofpropulsion system 113 based upon the disclosure herein of propulsionsystem 111.

In the illustrated embodiments, propulsion system 111 is shown includingnacelle 200 fixed relative to wing member 109 and disposed at theoutboard end of wing member 109. Nacelle 200 encloses and supports anengine 123. Engine 123, such as for example a turbine engine, and partsof a torque transfer mechanism that provide power to a proprotor gearbox(PRGB) 125 to drive rotor blades 119, all as disclosed in U.S. Pat. No.9,174,731, the entire content of which is hereby incorporated byreference.

As shown in FIGS. 3A-3B and 4, proprotor housing 202 rotates relative tothe nacelle 200 as the aircraft transitions between the forward flightmode (airplane mode) and the vertical flight mode (helicopter mode). Inforward flight mode, as shown in FIG. 3B, proprotor housing 202 isoriented generally horizontally and can form a recess or indentation 202r in an aft portion 202 a of the proprotor 202. Recess 202 r permitsclearance during rotation of the proprotor housing 202; however, recess202 r can provide a significant source of aerodynamic drag to theaircraft 101. Door 204 is connected to an aft portion of proprotorhousing 202 and nacelle 200. Door 204 can provide an aerodynamic surfaceto cover recess 202 r. In some embodiments, door 204 can protectadjacent components from environmental or other exterior elements orforces while being sufficiently stiff to avoid vibration or deflection.

In forward flight mode, as shown in FIGS. 3A and top of FIG. 4,proprotor housing 200 is in a horizontal orientation 50 and door 204 isin a closed position 60 to provide an aerodynamic profile to propulsionsystem 111. During conversion (transition) mode 52, as shown in themiddle of FIG. 4, proprotor housing 200 is in a non-horizontalorientation 52 and door 24 is in at least a partially opened position 62to accommodate movement of the movable proprotor housing 202 upward ordownward. In vertical flight mode, as shown at the bottom of FIG. 4,proprotor housing 200 is in a non-horizontal orientation, which can be agenerally vertical orientation 54, and door 204 is in an open position64. When door 204 is in closed position 60, door can provide anaerodynamic profile to the propulsion system 111, can cover recess 202r, and/or can cover any gap between proprotor housing 202 and nacelle200.

In certain exemplary embodiments shown in FIGS. 5A-12, door 204 can beconfigured to be connected to the proprotor housing frame 202 a by hingefittings 208 disposed at the forward portion 204 f of door 204, as shownin FIGS. 5B, 5C, and 7, or other connector mechanism that allows theproprotor housing 202 to be rotated relative to nacelle 200. In someembodiments, hinge fittings 208 can be disposed on at least one of theoutboard side 204 o and inboard side 204 i of door 204.

Door 204 is connected to nacelle 200 by a linkage 213. In someembodiments, linkage 213 is disposed on an aft portion 204 a of door204. In other embodiments, linkage 213 is disposed on at least one ofthe outboard side 204 o and inboard side 204 i of door 204.

In the illustrated embodiment, linkage 213 includes a roller trackassembly 211 including a roller track 212 fixedly mounted externally tonacelle 200 and a door roller mechanism 214 that rides on the rollertrack 212. In an embodiment, roller track 212 is mounted in top surface200 t of the aft portion 200 a of the nacelle 200. Roller track 212 canbe attached by fasteners to bulkheads and/or frames 200 a of nacelle 200support structure, FIG. 6. Roller track 212 defines a rolling directionRD of the door 204, FIGS. 5A and 6, in response to rotation to theproprotor housing 202 during conversion between the forward flight modeand the vertical flight mode of the aircraft. That is, door 204 can moveback and forth in the rolling direction RD in response to rotation ofthe proprotor housing 202 during flight mode transitions.

In certain embodiments, the door roller (bogie) mechanism 214 isconnected to structural extension 205 of the door 204, as shown in FIGS.7-8, as described below through a swivel joint 205 a. Door rollermechanism 214 is an assembly that can include a carriage member 215having a door attachment feature 217 that is connected to the structuralextension 205 of door 204, FIGS. 7-9. In certain embodiments, carriagemember 215 includes an upstanding plate including corrosion resistantstainless (CRES) steel or other suitable material. In certainembodiments, the door attachment feature 217 can comprise a sphericalbearing 223 connected to the door structural extension 205.

Referring to FIGS. 8-9, at least one roller 216 is disposed for rotationon a first side 215 f and on an opposite second side 215 d of thecarriage member 215 when the carriage member 215 is moved in the rollingdirection RD. In certain embodiments, the at least one roller 216includes multiple upper forward and aft rollers 226 a and multiple lowerforward and aft rollers 226 b disposed on each of the first side 215 fand the second side 215 d of the carriage member 215. The multiple upperforward and aft rollers 226 a and multiple lower forward and aft rollers226 b are separated by a space G adapted to receive a respective firstand second track members 320 and 322 described below. In certainembodiments, these rollers 226 a, 226 b are arranged in a rectangularpattern on each of the first side 215 f and the second side 215 d of thecarriage member 215 as depicted in FIGS. 8-9 in order to withstandnon-linear (angular directed) forces exerted on door 204 during aircraftoperation. It is contemplated that roller 216 could include a pluralityof rollers in various configurations (triangular, square, hexagonalpatterns) that can withstand non-linear (angular directed) forcesexerted on door 204.

Each roller 216 can be rotatably mounted on a respective fastener shaft219 that can be a through bolt and clamped up to the carriage member215. In an embodiment, each fastener shaft 219 extends through arespective passage through the carriage member 215 from one side to theother and includes a threaded end connected to a respective threaded nut227. Although upper roller 226 a on the first side 215 f and upperroller 226 a on the second side 215 d of the carriage member 215 areshown disposed on a common fastener shaft 219 for rotation, each rollercan be mounted by a respective individual fastener for rotation on thecarriage member 215. In one embodiment, each roller 216 can be aself-contained ball bearing with a non-rotating inner portion and arotating outer portion positioned tight against the carriage member 215.In certain exemplary embodiments, rollers 226 a, 226 b are made ofcorrosion resistant steel or other suitable material.

The initial positions of the upper rollers 226 a are adjusted by setscrews 221 that are slotted vertically in the carriage member 215. Theset screws 221 limit the range of travel of the bolts 219 for the upperrollers 226 a, which sets the distance between the upper rollers 226 aand lower rollers 226 b.

Referring again to FIGS. 8-9, first and second rub members 230, 232 aredisposed on the respective first and second sides 215 f, 215 d of thecarriage member 215 and are resiliently biased laterally outward awayfrom the carriage member 215 by one or more biasing elements 234disposed between first and second rub members 230, 232 and correspondingfirst or second side 215 f, 215 d of the carriage member 215. In certainembodiments, rub members 230, 232 are each slidably mounted on multiplefastener shafts 235 (four shown). In certain embodiments, rub members230, 232 each can be slidably mounted on the respective fastener shaftby a bushing. First and second rub members 230, 232 can be resilientlybiased to contact respective first and second sidewalls 320 s, 322 s ofthe respective track members 320, 322 in a manner to be described below.Each fastener shaft 235 extends through a respective passage in thecorresponding rub member 230, 232 and through the carriage member 215from one side to the other and includes a threaded end connected to arespective threaded nut 237.

In certain embodiments, rub members 230, 232 are each spring biased bymultiple coil bias springs (three shown in FIG. 9). The rub members 230,232 are spring biased in opposite lateral directions generallyperpendicular relative to the door rolling direction RD so as to contactthe respective first and a second sidewalls 320 s, 322 s, of the trackmembers, FIGS. 10 and 12, in a manner to dampen lateral vibrations ofdoor 204 attached to the door roller mechanism 214. Although multipleindividual biasing springs are shown between each rub member 230 and 232and the carriage member 215, alternative embodiments envisions use of asingle spring configuration that is disposed in a carriage memberthrough-hole (not shown) between the rub members 230, 232 to bias bothof the rub members. Moreover, other types of springs, such as leaf,cantilever, and other springs, can be used in certain embodiments.Further, resilient biasing elements other than springs, such as one ormore resilient bodies located as described above, can be used inpractice of certain embodiments.

Rub members 230, 232 can have a plate shape as depicted or any othersuitable shape. In certain embodiments, the rub members 230 and 232 aremade of aluminum-bronze alloy material, although any suitable materialcan be employed. An anti-friction coating optionally can be applied onthe outer surfaces of the rub members 230, 232. The anti-frictioncoating can be an anti-friction self-lubricating polymeric compositeliner in certain embodiments. In an embodiment, the anti-frictioncoating is Rexton 2000, which is a self-lubrication liner made byRexnord Corporation.

In certain embodiments, roller track assembly 211 includes a housing 300having flanges 302 and 303 with fastener holes. Housing flanges 302, 303are fastened to bulkheads and/or frames 200 a of the fixed portion 203of the respective nacelle 200 and 201 structure using fasteners throughthe fastener holes. In certain embodiments, housing 300 is made in twohalves which are assembled using fasteners received in holes in housingalignment flanges 305 shown in FIG. 10, although the housing 300 can bemade in one piece or any number of multiple other pieces. The assembledhousing 300 is precision located on the fixed portion 203 by lasertracking although conventional assembly methods using determinateassembly holes or tooling can be used. The assembled housing 300 definesthe door rolling direction RD for door 204 opening and closing.

Housing 300 includes a longitudinal channel 304 extending along itslength. Channel 304 includes a first entry end 304 a and a second endforming a deep stowage recess 304 b, FIGS. 10-11. Entry end 304 a isadapted to receive the door roller mechanism 214 during assembly of thedoor connection mechanism. To this end, entry end 304 a includes aninitial converging lead-in entrance 306 that communicates to adescending ramp insert 308, as shown in FIG. 12, to facilitate slidingof the rub members 230, 232 of the door roller mechanism 214 into thechannel 304. After assembly, the top of entry end 304 a is closed off bya cover plate 310 that prevents door roller mechanism 214 fromdisengaging from the door track assembly as the proprotor housing 202 isfully converted to the vertical flight mode during operation of theaircraft. Fasteners shown in FIG. 12 are used to attach lead-in rampinsert 308 and cover plate 310 to the housing 300.

Referring to FIGS. 10-12, housing 300 includes first and second tracks320, 322, which may be integral with or separate and connected to therespective housing flange 303, 302. Tracks 320, 322 receive rollers 226a, 226 b of the door roller mechanism 214 and extend generally parallelto one another along the length of the channel 304 until they curve anddescend at the remote end of the housing into the deep stowage recess304 b, whose shape and depth is selected to completely stow the doorroller mechanism 214 out of the way when door 204 is moved to the closedposition during the forward flight mode, as shown in FIG. 6.

First and second tracks 320, 322 extend inwardly from facing inner wallsof the housing 300 toward one another in a common substantiallyhorizontal plane and terminate short of one another to form a secondarychannel 323 therebetween, FIGS.10-12, through which the rub members 230,232 of the carriage member 215 of the door roller mechanism 214traverse.

First and second tracks each includes a respective upwardly facingsurface 320 d, 322 d and downwardly facing surface 320 e, 322 e. Thesesurfaces extend along the length of the tracks into the stowage recess304 b. Referring again to FIGS. 10-12, in certain embodiments, a wearresistant strip insert 330 is fastened to each of upwardly facingsurfaces and downwardly facing surfaces 320 d, 322 d; 320 e, 322 e toform wear resistant roller track surfaces. Wear resistant strip inserts330 are employed when housing 300 is made of material, such as analuminum alloy, that may suffer excessive wear from the carriage memberrollers 216 riding thereon during operation of the door roller mechanism214. Wear resistant strip inserts are attached by fasteners shown bestin FIG. 12 that are spaced apart along the length of the tracks 320,322. In certain embodiments, wear resistant strip inserts 330 are madeof CRES steel (the same material as the roller material), although othersuitable wear resistant materials can be used to this same end.

In certain other embodiments, the wear resistant strip inserts 330 maybe omitted if the housing 300 is made of a more wear resistant material,or if the housing is provided with more wear resistant roller tracksurfaces on the tracks 320, 322 by, for example, localized deposition ofa wear resistant track material on the tracks, localized heat treatment(e.g. localized laser hardening) of the tracks, or other localizedsurface hardening treatments to this end.

First and second tracks 320, 322 also include substantially vertical andparallel sidewalls 320 s, 322 s that face one another and are spacedapart to define the secondary channel 323 that receives the rub members230, 232 of the carriage member plate 215. Sidewalls 320 s, 322 s aretermed rubbed sidewalls in that the rub members 230, 232 are resilientlybiased by the springs or other biasing elements 234 to contact thesesidewalls as the door roller mechanism 214 traverses back and forthalong the roller tracks 320, 322 in the rolling direction RD.

Each of the sidewalls 320 s, 322 s includes an anti-friction coatingthereon to reduce fretting damage and/or wear resulting from contactwith the rub members 230, 232. An illustrative anti-friction coating tothis end comprises a composite coating including a matrix materialhaving anti-friction polymer particles dispersed in the matrix material,although other suitable composite or non-composite anti-frictioncoatings can be used. In certain embodiments, when the tracks 320, 322of the housing 300 comprises an aluminum alloy, a suitable compositecoating comprises an anodized aluminum (aluminum oxide) layer as thematrix material and polytetrafluoroethylene particles dispersed in theanodized layer. Such a coating can be formed on the surfaces ofsidewalls 320 s, 322 s by spraying or other suitable process.

Moreover, pursuant to certain embodiments, cover plate 310 preventsdisengagement of the door roller mechanism 214 from the roller trackassembly 211 as the proprotor housing 202 is fully converted to thevertical flight mode during operation of the aircraft, FIG. 7. Further,when the proprotor housing 202 is fully converted to the forward flightmode, the door structural extension 205 covers the recess 202 b and doorroller mechanism 214, FIG. 6. Door 204 can include an integral tailsection that is fastened on the structural extension 205 to this sameend.

Referring now to FIG. 13A, an alternative embodiment of a linkage 213′is illustrated. Linkage 213′ includes a pair of roller track assemblies(e.g., first roller track assembly 211 and second roller track assembly211′). Roller track assembly 211′ is substantially similar in form andfunction to roller track assembly 211. Thus, disclosure herein regardingassembly 211 is also applicable to assembly 211′. In the illustratedembodiment, as proprotor housing 202 rotates it causes door 204 and doorroller mechanisms 214, 214′ to translate aft respectively along track212, 212′ towards the aft portion 200 a of nacelle 200 in an openposition. The linkages 213, 213′ are shown and described with referenceto the proprotor housing 202 rotating relative to the nacelle 200, itwill be appreciated that at least one of the proprotor housing 202 andthe nacelle 200 can have various aerodynamic profiles and varyinginternal components. Accordingly, the shape and arrangement of thelinkages described herein can be also be configured for the particularaerodynamic profile and/or internal components (e.g., the track couldinclude a localized contour change to permit clearance from an internalcomponent).

Referring now to FIG. 13B, another embodiment of linkage 413 isillustrated. Linkage 413 includes at least one strut 442 coupled to door204 and nacelle 200. In an exemplary embodiment, linkage 413 comprises apair of struts 440. The pair of struts 440 is substantially similar inform and function to the roller track assembly 213, except as notedherein. Thus, disclosure herein regarding roller track assembly 213 isalso applicable to the pair of struts 413, except as noted herein. Inthe illustrated embodiment, the pair of struts 440 includes a firststrut 442 and a second strut 444. Struts 442, 444 can represent anycomponent that is capable to extend and retract longitudinally along thedirection L. In some embodiments, when door 204 is in the open positions62, 64, struts 442, 444 can resist longitudinal compression to securedoor 204 in a particular location above the nacelle 200. In anembodiment, struts 442, 444 can dampen the oscillations from theproprotor housing 202.

The forward portion 442 f, 444 f of each strut 442, 444 can includefastening ends 446, 448, respectively, each having a plurality offastener holes extending therethrough for securing to the interiorsurface of door 204. The aft portion 442 a, 444 a of each strut 442, 444can include fastening ends 447, 449, respectively, each having aplurality of fastener holes extending through for securing to theexterior surface of nacelle 200 and/or on a frame member 200 m ofnacelle 200. In some embodiments, the attachment locations for thestruts 442, 444 can be recessed locally in the nacelle 200 or covered bya contoured fairing. In an embodiment, flat fastening ends 446, 448 canrespectively be disposed at forward ends 442 f, 444 f of struts 442,444; however, it will be appreciated that aft ends 442 a, 444 f ofstruts 442, 444 can also be configured to include flat fastening endsfor securing to nacelle 200. In an embodiment, the aft ends 442 a, 444 aof the struts 442, 444 can be connected to or positioned on a framemember 200 m and/or on an interior or exterior surface of nacelle 200.Fastening ends 446, 448, 447, 449 can include a bearing housing topermit a pivoting motion for strut 442, 444 when the proprotor housing202 is in a non-horizontal position. In some embodiments, at least oneof the fastening ends 446, 448, 447, 449 can be a monoball style jointto avoid side loads.

In an exemplary embodiment, as shown in FIG. 13B, each strut 442, 444may be a telescoping strut. Each strut 442, 444 can include a pluralityof strut segments 452, 454, respectively, having various outer diametersto permit telescoping expansion and retraction. It is contemplated thateach strut 442, 444 could include a variety of configurations that caninclude two, three, four, five, six, seven, eight, nine, ten, or morestrut segments, 452, 454.

It is further contemplated that the struts 442, 444 could come in avariety of shapes and sizes. Struts 442, 444 are shown as generallycylindrical in shape. In other embodiments, struts are generally square,u-shaped, or other suitable shape to achieve a telescoping function.

Referring now to FIGS. 14A-14F, another embodiment of linkage 513 isillustrated. Linkage 513 includes a roller track 512 fixedly mounted todoor 204 and a roller mechanism 514 fixedly mounted to the nacelle 200.Roller track and roller mechanism 512, 514 are substantially similar inform and function to the roller track and door roller mechanism 214,except as noted herein. In the illustrated embodiment, roller track 512moves with door 204 as door 204 rotates into an open position 62, 64 andrides on roller mechanism 514. A forward portion 512 f of the rollertrack 512 is mounted to an interior surface in the forward portion 204 fof door 204 by conventional fasteners thereto (e.g., adhesives, screws,bolts). Roller track 512 can be rigidly connected to door 204 byintermediate supports 512 s connecting the two, as shown in FIGS. 14Aand 14D, or a web of intermediate supports 512 s′ between the doorinterior surface and the track 512, as shown in FIG. 14E.

In an exemplary embodiment, the roller mechanism 514 rolls within thetrack 512 attached to the door 204 such that the forward hinges 208 movethe proprotor housing 202 and drive the door 204 and track 512 throughthe fixed roller mechanism 514. This forces an orientation of the door204 as it moves aft with the proprotor housing 202. The geometry oftrack 512 is defined to control the orientation of the door 204 for adesired aerodynamic profile and to avoid contact with adjacent structureas it moves. In an exemplary embodiment, as proprotor housing 202rotates to a non-horizontal position 52, 54, door 204 pivots at hingefittings 208 and track 512 moves with door 204 being retained by theroller mechanism 514. In an exemplary embodiment, as shown in FIG. 14F,track 512 can include a first and second tracks 520, 522 that define achannel N for receiving shaft 517 of roller mechanism 514. The end ofaft portion 512 a of the roller track 512 is connected to the rollermechanism 514 when door 204 is approaching or in a closed position, asshown in 14B.

Roller mechanism 514 includes at least one roller 516 rotatablyconnected to a shaft 517, as shown in FIG. 14F. Roller 516 can include afirst and second rollers 516 a, 516 b that the first and second tracks520, 522 ride on during movement of door 204. In an embodiment, a secondset of rollers similar to the first and second rollers pair of rollers516 a, 516 b can be disposed below rollers 516 a, 516 b to furtherconstrain the path of the track and provide rigidity to the structure.In an embodiment, rollers 516 a, 516 b can dampen vibrations from door204. Shaft 517 can be mounted on the base 200 s of the nacelle 200 usingconventional fasteners (e.g., adhesives, screws, bolts).

Referring now to FIG. 15A, an embodiment of linkage 613 is illustrated.Linkage 613 can be a hinge member 650 that pivots in a pivot direction Pas the proprotor housing 202 rotates. Hinge member 650 can include firstand second hinge joints 652 a, 652 b each including a hinge pin 654rigidly attached to and extend from proprotor housing 202. Hinge pin 654is configured to engage with one or more bearings 656 attached to theinboard or outboard side 204 i, 204 o of the door 204. Thus, first andsecond hinge joints 652 a, 652 b are oriented to rotate about a rotationaxis R to permit door 204 to pivot about hinge pins 654 when proprotorhousing 202 is in a non-horizontal position. First and second hingejoints 652 a, 652 b can be disposed on outboard and inboard sides ofdoor 204 to hingedly couple door 204 to proprotor housing 202.

It will be appreciated that the contemplated embodiment shown in FIG.15A is configured to allow pivoting movement of door 204 at hinge member650 from about 0 degrees to 90 degrees relative to the longitudinal axisof the proprotor housing 202. The pivot movement of the hinge member 650can permit the door 204 to rotate behind the proprotor housing 202 whenin a non-horizontal position and retains the door 204 when the proprotorhousing 202 is in a horizontal position. When the proprotor housing 202is in a vertical position 54, the door is generally in a 90 degreesorientation and the nacelle base portion 200 s functions as a backstopthat the aft end 204 a rests thereon. In some embodiments, the nacellebase portion 200 s can include a reinforced portion for the load and/orsliding of the door 204 (e.g., a local rub strip of metal or Teflon)thereon and to limit wear on the nacelle base portion 200 s.

Referring now to FIG. 15B, another embodiment of linkage 613′ isillustrated. Linkage 613′ can be a hinge member 650′ that pivots in apivot direction P as the proprotor housing 202 rotates. Hinge member650′ can include first and second hinge joints 652 a′, 652 b′ disposedon opposite ends of arm 652 c′. First hinge joint 652 a′ can be adjacentto the forward portion of door 204 and is configured to be at leastpartially in a slot 202 s in the proprotor housing 202 for movingtherewith. Second hinge joint 652 b′ is coupled to the forward edge ofthe nacelle base portion 200 s and adjacent to the aft portion of door204. First and second hinge joints 652 a′, 652 b′ extend respectivelyfrom the proprotor housing 202 and the nacelle base portion 200 s. Arm652 c′ can be coupled to the interior surface of the door 204 and isconfigured to impart movement from the first hinge joint 652 a′ tosecond hinge joint 652 b′ when proprotor rotates about rotation axis R.When proprotor housing 202 moves upward, the linkage 613′ causes door204 to rotate generally vertically. When proprotor housing 202 movesdownward, the linkage 613′ causes door 204 toward a horizontal position.

It will be appreciated that the contemplated embodiment of linkage 613′is configured to allow pivoting movement of door 204 at hinge member650′ from about 0 degrees to 90 degrees relative to the longitudinalaxis of the proprotor housing 202. The pivot movement of the hingemember 650′ can permit the door 204 to rotate behind the proprotorhousing 202 when in a non-horizontal position and retains the door 204when the proprotor housing 202 is in a horizontal position. When theproprotor housing 202 is in a vertical position 54, the door 204 isgenerally in a 90 degrees orientation.

Linkages 613, 613′ are exemplary embodiments of hinge members that canbe used to move door 204 when the proprotor housing 202 is in anon-horizontal position. It should be appreciated that linkages 613,613′ may take on a wide variety of hinge configurations and the hingescan be located at various positions on the proprotor housing 202 and/ornacelle 200. Linkage 613, 613′ can advantageously provide a mechanicalconnection that can prevent or minimize mechanical seizure (e.g.,binding).

Referring to FIG. 16, an embodiment of door 704 is illustrated thatincludes a flexure portion 704 m, 704 n. A forward portion 704 f of door704 is fixedly connected to the aft portion 202 a of proprotor housing202 and an aft portion 704 a of door 704 is fixedly connected to thebase portion 200 s of the nacelle 200. In one embodiment, the flexureportions 704 m, 704 n bend and can permit the door 704 to fold on itselfin response to rotation of the proprotor housing 202 in a non-horizontalorientation 50, 52. Flexure portions 704 m, 704 n extend and aregenerally oriented horizontally, straight, and/or planar when proprotorhousing 200 is a horizontal orientation 50, 52.

Flexure portions 704 m, 704 n can be disposed in the forward and aftportions 704 f, 704 a of the door 704. It is contemplated that there canbe more or less flexure portions 704 m, 704 n (e.g., one, three, four,five, six, seven, eight, nine, or more flexure portions 704 m, 704 n)that can be oriented in various configurations to permit folding of door704 during rotation of proprotor housing 202 in a non-horizontalposition. In an embodiment, the flexure portions 704 m, 704 n can permitrolling of the door 704 onto a spindle associated with the proprotorhousing 202 and/or the nacelle 200 to collect excess material.

In some embodiments, at least one flexure portion 704 m, 704 n can be acomposite material. The composite material can be comprised of a matrixmaterial and a reinforcement material. The reinforcement material cancomprise a plurality of reinforcement layers configured to provideflexibility to the door 704 such that at least part of the compositematerial may fold, bend, or roll in response to rotation of theproprotor housing 202. In some embodiments, the entire door 704 iscomprised of a composite material that can include flexure portions 704m. 704 n.

In an embodiment, at least one flexure portion 704 m, 704 n can be afabric, textile, and/or an e-textile. The e-textile can be a smartfabric that is a fabric with digital components and electronics embeddedtherein to adjust a property of the fabric. In a particular embodiment,the e-textile can be configured to permit flexure portions 704 m, 704 nto bend when proprotor housing 202 is in a non-horizontal position. Alsoshrinkage of the e-textile is possible to keep the material taunt formaximum aerodynamic and sealing benefit. In an embodiment, door 704 iscomprised entirely of a fabric, textile, and/or e-textile.

An embodiment provides that at least one flexure portion 704 m, 704 n isa rigid material that is configured to be folded onto itself. In someembodiments, flexure portions 704 m, 704 n can include a hinge joint.The hinge joint can include a plurality of hinges along the flexureportion 704 m extending from the outboard and inboard sides 704 o, 704 iof the door 704. In some embodiments, door 704 is made from a rigidcomposite or metallic material including the flexure portions 704 m, 704n.

Referring now to FIG. 17A, an embodiment including a plurality of doors804 is illustrated. The plurality of doors 804 includes a first door 870and a second door 872 disposed on the outboard and inboard sides of thenacelle 200, respectively. Each of first and second doors 870, 872 canbe folded in to a closed position with first and second doors 870, 872forming an aerodynamic shape when the proprotor housing 202 is in ahorizontal position 50, as shown in FIG. 3A. When proprotor housing 202is a non-horizontal position, each of first and second doors 870, 872pivots open at hinge joints 808, as shown in FIG. 17A.

In an embodiment, each of first and second doors 870, 872 can beassociated with an actuator 874, 876. Each of the actuators 874, 876 isconfigured to open and close first and second doors 870, 872,respectively, when the proprotor housing 202 is in a non-horizontalposition. In an embodiment, each actuator 874, 876 can be a linearactuator, a rotary actuator, or still another type of actuator that maybe powered hydraulically, electrically, or still otherwise powered. In aparticular embodiment, each of the actuator mechanisms 874, 876 can belinked to the PRGB gearbox 125. The PRGB gearbox 125 can mechanicallydrive the actuators 874, 876.

In another embodiment, the first and second doors 870, 872 can be gangedtogether by an interconnect shaft 877 to provide for even opening andclosing. In an embodiment, interconnect shaft 877 can be coupled to anactuator 878, which can rotate interconnect shaft 877 to open and closethe first and second doors 870, 872. Actuator 877 can be a linearactuator, a rotary actuator, or still another type of actuator that maybe powered hydraulically, electrically, or still otherwise powered. In aparticular embodiment, actuator 878 can be a hydraulic cylinder disposedin the middle of the first and second doors 870, 872 that can open andclose the doors 870, 872 through a toggle linkage.

Still in other embodiments, shown in FIGS. 17B-17C, the first and seconddoors 870, 872 are configured to open and close with the proprotorhousing 202 or PRGB gearbox 125 with a sliding door linkage 813′. In anembodiment, first and second doors are mechanically connected via thedoor linkage 813′ to the proprotor housing 202 or gearbox 125 such thatfirst and second doors 870, 872 flip open when the proprotor housing 202is in a non-horizontal orientation 52, 54 and flip closed when in ahorizontal orientation 50. In an exemplary embodiment shown in FIG. 17B,door linkage 813′ includes a first sliding member 874′ and a secondsliding member 876′. Each of first and second sliding members 874′, 876′are associated with the first and second doors 870, 872, respectively(e.g., first and second sliding members 874′, 876′ can be movablyconnected to the interior surface of the first and second doors 870,872). At least one of or both of the first and second sliding members874′, 876′ are movably connected to the proprotor housing 202 or PRGBgearbox 125 such that as the proprotor housing 202 moves in anon-horizontal orientation, first and second sliding members 874′, 876′move at least partially away or toward each other; thus, opening andclosing the first and second doors 870, 872 therewith.

In another embodiment, shown in FIG. 17C, sliding door linkage 813″ caninclude a first pinned linkage 874″ and a second pinned linkage 876″each associated with a slot 870 s, 872 s in the first and second doors870, 872, respectively. As the proprotor housing 202 pivots upward anddownward, each of the pinned linkages 874″, 876″ slide with the PRGBgearbox 125 in the respective slot 870 s, 872 s to allow sliding of thefirst and second doors 870, 782 as the proprotor housing 202 pivots fromhorizontal orientation 50 to non-horizontal orientations 52, 54. Doorlinkage 813″ can advantageously provide a close connection betweenproprotor housing 202 and first and second doors 870, 872 and canprevent or minimize mechanical seizure (e.g., binding).

It should be understood that a wide variety of a plurality of doors 804and passive and active mechanisms for opening and closing the pluralityof doors 804 may be utilized; for example, and not limitation, similarto bomb bay doors and mechanisms including a hydraulic cylinder disposedin the middle of the first and second doors 870, 872 that toggles thedoors open and closed.

Practice of certain embodiments are advantageous for use with the doorsof a tiltrotor aircraft of the type described to dampen vibrations fromthe proprotor housing 202. However, the embodiments herein are notlimited to practice in connection with tiltrotor aircraft doors and canbe practiced with respect to other door applications for aircraft,helicopters, and other non-aircraft vehicles to dampen unwantedvibrations.

Referring now to FIGS. 18A-18B and 19, a proprotor 973 for a propulsionsystem 111 is illustrated. Proprotor 973 is similar in form and functionto the proprotor housing 202, except as noted herein. Proprotor 973 canbe coupled to a nacelle 200. Proprotor 973 can include a forward portion974 and an aft portion 976. The forward portion 974 includes a pluralityof rotor blades 119 and gearbox 125. Forward portion 974 is configuredto selectively pivot between a horizontal orientation and anon-horizontal orientation about a conversion axis C, as shown in FIGS.18A-18B. When the forward portion 974 is in a non-horizontal orientation952, 954, the aft portion 976 is in a horizonal orientation. In anembodiment, the conversion axis C is disposed in the forward portion 974of the proprotor 973. When the forward portion 974 is in a horizontalorientation 950, the aft portion 976 is in a horizontal orientation.

Proprotor 973 can be disposed on an outboard end of a wing member 980.Wing member 980 includes a first rib 982 and a second rib 984. In anexemplary embodiment, first rib 982 is the most outboard rib of the wingmember 980. Wing member includes a forward spar 985, an aft spar 986,and a cove spar 987. An interconnect drive shaft 988 is disposed betweenthe forward spar 985 and aft spar 986. The interconnect drive shaft 988provides a torque path that enables a single engine to provide torque toboth proprotors 111 and 113 in the event of a failure of the otherengine. In the embodiment, the second portion 976 is rigidly attached tothe aft spar 986 and cove spar 987 and remains in horizontal positionwhile the forward portion 974 can be in horizontal 950 andnon-horizontal orientations 952, 954.

A pivot mechanism 990 pivots the forward portion 974 between horizontaland non-horizontal orientations 950, 952, 954. The pivot mechanism 990includes a cantilevered spindle 992 and an actuator 994. In an exemplaryembodiment, the cantilevered spindle is disposed between first rib 982and second rib 984 and the actuator 994 can be a rotary actuatordisposed outboard of first rib 982. Bearings 996 can be associated withthe first and second ribs 982 to support the cantilevered spindle 992.To pivot the forward portion 974, the rotary actuator 994 engages thespindle 992. It should be appreciated that pivot mechanism may take on awide variety of configurations. For example, the forward portion 974could be mechanically driven by a linear actuator in the outboard end ofwing 980.

In some embodiments, proprotor 973 can be coupled to a nacelle 200. Inan embodiment, the aft portion 976 of proprotor 973 is a stationaryaerodynamic fairing. In other embodiments, the aft portion 976 enclosesand supports an engine 123. In an embodiment, proprotor 973 can have alength that is longer than conventional proprotors, e.g., proprotorhousing 202.

The illustrative embodiments described herein can advantageously providea door that covers a recess aft of the proprotor or other aerodynamicconfiguration during forward flight (horizontal orientation) to reducedrag while maintaining structural integrity and stiffness.

Referring now to FIGS. 20-26, an embodiment of a door system 1210 isillustrated. The door system 1210 is designed for the nacelle 200 of atiltrotor aircraft 101 as shown in FIGS. 1-2 and described herein. In anembodiment, as shown in FIG. 20, the nacelle 200 includes a movableproprotor housing 202 rotatable relative to a fixed portion 203 of thenacelle 200 from a forward flight mode, as shown in FIG. 2, to avertical flight mode, as shown in FIG. 1. The nacelle 200 includes aproprotor gearbox door 204 connected to the movable proprotor housing202 and pivotably coupled to the fixed portion 203. The door system 1210includes a track assembly 1532 mounted to the movable proprotor housing202 and a door roller mechanism 1514 connected to the proprotor gearboxdoor 204. The door roller mechanism 1514 traverses the track assembly1532 during rotation of the movable proprotor housing 202.

In certain exemplary embodiments, shown in FIGS. 22-23, the door systemincludes a linkage 1613 to pivotably couple the door 204 to the fixedportion 203 of the nacelle 200. The linkage 1613 is disposed in the aftportion 204 a of the door 204. In an embodiment, as shown in FIGS.21-24, the linkage 1613 is comprised of at least one hinge member thatpivots in a pivot direction P1 as the proprotor housing 202 rotates. Inan embodiment, the at least one hinge member is comprised of a pair ofhinge members. In an embodiment, the pair of hinge members is comprisedof first and second hinge members 1650 a, 1650 b. Second hinge member1650 b is substantially identical to first hinge member 1650 a; for thesake of efficiency, only the features of the first hinge member 1650 aare shown in FIG. 23. However, one of ordinary skill in the art wouldfully appreciate an understanding of the second hinge member 1650 bbased on the illustrations in the FIGS. 22-23 and the descriptionherein. First and second hinge members 1650 a, 1650 b can each include ahinge joint 1652 a, 1652 b, respectively, with a hinge pin 1654 a, 1654b. The hinge joints 1652 a, 1652 b are disposed on a bracket end 1653 a,1653 b and first ends 1651 a, 1651 b of the respective hinge member 1650a, 1650 b. In an embodiment, the bracket ends 1653 a, 1653 b aredisposed on a stationary surface of the fixed portion of the nacelle 200to hingedly couple door 204 to the fixed portion 203 of the nacelle 200.In an embodiment, the stationary surface is a bottom surface 203 s ofthe fixed portion 203, as shown in FIG. 23. In some embodiments, thestationary surface is a surface on the bulkheads and frames 200 of thefixed portion 203 of the nacelle 200. In an illustrative embodiment, thehinge joints 1652 a, 1652 b are disposed on a stationary surface in aforward portion of the fixed portion 203 of the nacelle 200.

The hinge members 1650 a, 1650 b each include a rigid arm portion 1656a, 1656 b with first ends 1651 a, 1651 b and second ends 1657 a, 1657 bopposite from the respective first ends 1651 a, 1651 b and a curvedportion 1655 a, 1655 b disposed between the respective first and secondends. The second ends 1657 a, 1657 b of the hinge members 1650 a, 1650 bare each rigidly attached to aft portion 204 a of the door 204. In anembodiment, the second ends 1657 a, 1657 b are disposed on the bottomssurface 204 s of door 204. The curvature of the curved portion 1655 a,1655 b is configured to permit the door 204 to pivot between forwardflight mode (e.g., the door 204 is generally horizontal) and verticalflight mode (e.g., the door is generally vertical). In an embodiment,the hinge members 1650 a, 1650 b are each a gooseneck hinge. It shouldbe noted that hinge members 1650 a, 1650 b are merely an example oflinkage 1613 and other linkage configurations can be implemented. Forexample, linkage 1613 can be comprised of more or less hinge members(one, three, four, or more) and/or of other joint assemblies capable ofpivoting in a pivot direction P1 as the proprotor housing 202 rotates tomovably pivotable couple the door 204 to the fixed portion 203 of thenacelle 200.

Referring to FIGS. 21-24, the door roller mechanism 1514 is disposed onthe bottom surface 204 s in the forward portion 204 f of the PRGB door204. The door roller mechanism 1514 is an assembly that can include atleast one roller 1516 rotatably connected to a shaft 1517 associatedwith door 204 via a support member 1519. The at least one roller 1516can be comprised of one roller mounted to a first end 1517 a of shaft1517. In an embodiment, at least one roller 1516 can include first andsecond rollers 1516 a, 1516 b mounted to shaft 1517. In an embodiment,the roller 1516 is composed of a vibration damping material for dampingvibrations from the movable proprotor housing 202 and door 204. In somecontemplated embodiments, the at least one roller 1516 can be a rollingelement or assembly including at least one of the following bearingssupported by a bearing housing, slide bearings, and the like. The atleast one roller 1516 can be a comprised of a plurality of rollers 1516a, 1516 b arranged in a configuration (triangular, rectangular pattern)that rotate within and/or on track assembly 1532 and can withstand theoperational forces exerted on the door 204.

Shaft 1517 can be pivotably mounted via pin 1518 to the support member1519. In an embodiment, shaft 1517 includes a bracket for receiving pin1518 therethrough on the second end 1517 b. Support member 1519 isdisposed on the bottom surface 204 s of door 204 and is configured tosupport a load from the door roller mechanism 1514 (e.g., the shaft 1517and the roller 1516). The support member 1519 can include an extensionmember 1519 e that extends downward and beyond a base portion 1519 b.The extension member 1519 e includes an extension bore 1521 to receivepin 1518 therein. The extension member 1519 e provides support for thevibration and pivoting forces exerted on door 204 during operation. Insome embodiments, the extension member 1519 e and the base portion 1519b are configured to withstand operational forces and absorb vibrationsthat occur during operation. For example, the extension member 1519 eand/or base portion 1519 b can include an internal hollow portionhousing a vibration damping member or material to reduce forces andvibrations on the door 204.

In some embodiments, the support member 1519 can include a brace member1523 disposed on the bottom surface 204 of door between the inboard side204i and the outboard side 204 o. The brace member 1523 can extendthrough a brace bore 1525 and is configured for rigidly transferringvibrations between the door 204 and the support member 1519. In someembodiments, brace member 1523 can absorb vibrational forces. Bracemember 1523 can be constructed of a rigid and/or flexible structuralmember (e.g., metal, composite, and/or polymeric material). It should beappreciated that the door roller mechanism 1514 can be modified toinclude a plurality of brace members 1523. In an alternative embodiment,the support member 1519 and brace member 1523 may be integrated orseparate components.

The track assembly 1532 defines a rolling direction RD of the at leastone roller 1516 disposed therein. The track assembly 1532 includes atleast one track 1534 being a substantially straight guiding structure.The at least one track 1534 includes sidewalls 1535 and a floor 1537that define a channel N for receiving the roller 1516. The sidewalls1535 include lip portion 1536 for securing the roller 1516 therein. Theat least one track 1534 can include, but is not limited to, rail, bar,conduit, and the like. In some embodiments, the track 1534 isconstructed of metallic and/or composite materials. In some embodiments,track assembly 1532 includes a plurality of tracks.

In an embodiment, the track assembly 1532 includes a flange 1538 mountedto exterior surface of the sidewalls 1535 for securing the trackassembly to the movable proprotor housing 202. The track 1534 caninclude an entry end 1539 a that is adapted to receive the roller 1516therein during assembly and to prevent disengagement of the roller 1516.The entry end 1539 a can be removable to provide access to the roller1516 for installation and maintenance. In an embodiment, shown in FIG.25, the entry end 1539 a disposed at the aft portion of the track 1534are removable and provide a space G to receive the shaft 1517 when inforward flight mode. Opposite to the entry end 1539 a is a stopper end1539 b, shown in FIG. 23, disposed at the forward portion of the track1534 and prevents disengagement of the roller 1516 when in the track isin a vertical flight mode.

In some embodiments, as shown in FIG. 26, the track 1534 can include acurved portion 1533 shaped to complement a curvature of the movableproprotor housing 202 and, in some embodiments, to provide clearanceand/or assist the movable proprotor housing 202 as it rotates to avertical flight mode. In an illustrative embodiment, the curved portion1533 can include a stowage recess 1531 to stow the roller 1516 and shaft1517 when in a forward flight mode. In other embodiments, the curvedportion 1533 can include an ascending portion and/or a descendingportion.

In an embodiment, the movable proprotor housing 202 provides a surfacefor supporting the track assembly 1532. In an embodiment, as shown inFIG. 23, the track assembly 1532 is mounted to the bottom surface 202 sof the movable proprotor housing 202. In other embodiments, the trackassembly 1532 is mounted to the top surface 202 t of the movableproprotor housing 202. The movable proprotor housing 202 includes achannel opening 202 a with two symmetrical sides and an opening at theaft end 202 a of the housing 202. In some embodiments, the trackassembly 1532 can be mounted to the frame supporting the movableproprotor housing 202 and disposed in the channel opening 202 a. In anembodiment, the track assembly 1532 is coupled to the movable proprotorhousing 202 using conventional fasteners secured through the flange1538.

During operation, when in forward flight, the roller 1516 resides in thechannel N at the aft end of the track assembly 1532, as shown in FIGS.20-21 and 23. In an illustrated embodiment, as shown in FIG. 23, theshaft 1517 pivots to a substantially horizontal position to provide anarrow profile in the interior of the nacelle 200.

When the movable proprotor housing 202 is in a non-horizontal position,as shown in FIG. 22, the track assembly 1532 moves therewith, whichcauses the at least one roller 1516 to roll in a rolling direction RDwithin the channel N of the track 1534 and causes the linkage 1613 topivot in a pivot direction P1. The linkage 1613 rotates only at thehinge joints 1652 a, 1652 b and is otherwise rigid (e.g., rigid portionwith curved portion 1655 a, 1655 b). When the movable proprotor housing202 is rotating upward, the roller 1516 moves upward within the track1534 and the door 204 is positioned to at least a partially openedposition 62. In vertical flight mode, the proprotor housing 202 has agenerally vertical orientation 64, and the roller 1516 is positioned ina forward portion of the track 1532 and the door 204 is in an openposition (e.g., generally vertical), as shown in FIG. 22. Conversely,roller 1516 moves downward when the movable proprotor housing 202 isrotated downward. Advantageously the at least one roller 1516 connectionwith the track 1534 in the movable proprotor housing 202 can reduce someof the vibration transferred to the door 204 because it provides asingle attachment point therebetween (as opposed to two attachmentpoints). Similarly, the configuration of the linkage 1613 between thedoor 204 and the fixed portion 203 of the nacelle 200 serves to limitrelative motion between the forward and aft door 204 attachment points.

The door system 1210 advantageously provides a system that slaves thePRGB door 204 to the position of the proprotor housing 202, which allowsthe door 204 to rotate without requiring additional actuation. Inaddition, the door system 1210 can facilitate installation andmaintenance by having only a primary wear component being the roller1516 and being located at easy to access and view locations (e.g.,personnel can view the primary wear component easily when viewing thetop of the proprotor housing 202 in the forward flight mode). Moreover,the door system 1210 is a compact, lightweight system.

It may be advantageous to set forth definitions of certain words andphrases used in this patent document. The term “couple” and itsderivatives refer to any direct or indirect communication between two ormore elements, whether or not those elements are in physical contactwith one another. The terms “include” and “comprise,” as well asderivatives thereof, mean inclusion without limitation. The term “or” isinclusive, meaning and/or. The phrases “associated with” and “associatedtherewith,” as well as derivatives thereof, may mean to include, beincluded within, interconnect with, contain, be contained within,connect to or with, couple to or with, be communicable with, cooperatewith, interleave, juxtapose, be proximate to, be bound to or with, have,have a property of, or the like. The term “proprotor housing” refers tothe exterior housing and can refer to internal components (e.g., gearbox125 and other components) within the proprotor housing 202.

Terms such as “first” and “second” are used only to differentiatefeatures and not to limit the different features to a particular orderor to a particular quantity.

At least one embodiment is disclosed and variations, combinations,and/or modifications of the embodiment(s) and/or features of theembodiment(s) made by a person having ordinary skill in the art withinthe scope of the disclosure. Alternative embodiments that result fromcombining, integrating, and/or omitting features of the embodiment(s)are also within the scope of the disclosure. Use of broader terms suchas comprises, includes, and having should be understood to providesupport for narrow terms such as consisting of, consisting essentiallyof, and comprised substantially of. Accordingly, the scope of protectionis not limited by the description set out above but is defined by theclaims that follow, the scope including all equivalents of the subjectmatter of the claims. Each and every claim is incorporated as furtherdisclosure into the specification and the claims are embodiment(s) ofthe present invention.

What is claimed is:
 1. An aircraft, comprising: a nacelle configured asa housing for an engine and disposed at a fixed location relative a wingmember; a proprotor housing coupled to the nacelle, the proprotorhousing configured to selectively rotate between a horizontalorientation and a non-horizontal orientation; a door hingedly coupled tothe proprotor housing by a first hinge joint and hingedly coupled to thenacelle by a second hinge joint, wherein the first and second hingejoints are configured to move the door from a closed position when theproprotor housing is in a horizontal orientation to an open positionwhen the proprotor housing is in a non-horizontal orientation.
 2. Theaircraft according to claim 1, further comprising an arm disposedbetween the first and second hinge joints, the arm configured to impartmovement from the first hinge joint to the second hinge joint.
 3. Theaircraft according to claim 1, wherein the first hinge joint is at leastpartially disposed in a slot in the proprotor housing.
 4. An aircraft,comprising: a proprotor coupled to a wing member, the proprotorcomprising a forward portion and an aft portion; wherein the forwardportion is configured to selectively pivot between a horizontalorientation and a non-horizontal orientation about a conversion axis C;and wherein when the forward portion is in a non-horizontal orientation,the aft portion is in a horizonal orientation.
 5. The aircraft accordingto claim 4, wherein the conversion axis C is disposed in the forwardportion of the proprotor.
 6. The aircraft according to claim 4, whereinthe wing member comprises a first rib and a second rib.
 7. The aircraftaccording to claim 6, wherein the forward portion is actuated by acantilevered spindle disposed outboard of the second rib.
 8. Theaircraft according to claim 6, further comprising bearings to supportthe cantilevered spindle, the bearings are associated with the first andsecond ribs.
 9. The aircraft according to claim 6, wherein an actuatoris disposed outboard of the first rib and is configured to engage thecantilevered spindle to pivot the forward portion in a non-horizontalorientation.